1. Field of the Invention
The present invention relates to a photomultiplier and, more particularly, to an electron multiplier for constituting the photomultiplier and cascade-multiplying photoelectrons emitted from a photocathode in correspondence with incident light by multilayered dynodes.
2. Related Background Art
Conventionally, photomultipliers have been widely used for various measurements in nuclear medicine and high-energy physics as a .gamma.-camera, PET (Positron Emission Tomography), or calorimeter.
A conventional electron multiplier constitutes a photomultiplier having a photocathode. This electron multiplier is constituted by anodes and a dynode unit having a plurality of stages of dynodes stacked in the incident direction of an electron flow in a vacuum container.